JPS62162508A - Method and device for forming pellet - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus and method for forming pellets.

Pellet pellets are often formed by extruding a strand and cutting it into pieces. However, the cutting action will tend to crush the pellet if the pellet has square ends (i.e., ends perpendicular to the axis of the pellet).
If pellets are required, they must be made by compression. Compaction methods are undesirable because they are slow and expensive, or in the case of catalyst pellets consisting of porous materials, the pellets formed may have a reduced porosity for compaction.

In the production of catalyst pellets, the edges of the pellets may have a uniform shape and a "square shape" in order to pack them into the catalyst bed and to facilitate the infiltration of the reaction system and products into the pellets. There are some things that are desirable. Catalyst pellets are generally produced by shaping the material of the pellet in a deformable or "plastic" state (commonly referred to in the ceramic industry as the "green" state, and this term does not refer to the color of the material); It is made by heat treating it to harden it into a hard form. If the material is to be extruded in a plastic state and then cut to form pellets, it is generally preferable to cut the material while it is still in a plastic state, because after heat treatment the hard material is cut by the blade that cuts it. This is because it requires the use of a worn diamond saw blade. However, in the plastic state, the pellets collapse during cutting.

Catalyst pellets are produced by extruding and cutting a deformable material to form pellets, heat treating the pellets to harden and burn off any organic material present, and then coating the hard pellets with a catalytically active material. make often. Prior to being coated with catalytically active substances, the solid pellets can be considered catalyst supports. For example, hollow pellets, which are hollow cylindrical pellets, are particularly susceptible to collapse in the deformable plastic state and, for example, in the ICI patent case.
A generally cylindrical pellet having several small holes extending parallel to its axis, such as those described in European Patent Application No. 85307070, is susceptible to some of the holes becoming obstructed if crushed.

For example, pellets with external protrusions that are of a "star" or "cogwheel" cross-section are also susceptible to crushing.

How to solve cl'1 problem: If the extruded strand is cut horizontally by passing a blade downwards by gravity, it passes through the strand horizontally.
It has been found that pellet crushing can be reduced and the edges of the pellets made more perpendicular to the pellet axis.

Accordingly, the present invention involves extruding a strand of deformable pellet-forming material, feeding the strand downward by gravity and passing a blade substantially horizontally through the strand to cut the strand horizontally and leaving the strand in a deformable state. The process consists of separating the pellets from it during the process.

The present invention also provides a method of forming a hard heat resistant pellet comprising extruding a strand of deformable material, cutting the strand to separate the pellets therefrom, heating the pellet to form a hard heat resistant pellet, and forming a hard heat resistant pellet. The pellets are separated from the strands by passing the strands downwardly by gravity and cutting the strands substantially horizontally therethrough.

The strands can be of any desired cross section, e.g. rectangular,
It may be round, annular or hexagonal, and may be hollow or contain several holes inside.

3 strands! ! Continuous extrusion is convenient, in which case the cutting blade is moved at the same speed and in the same direction as the strand while advancing the cutting blade across the strand, thereby achieving a precise "square" cut. However, by allowing a significant length of the strand to hang down without much restraint from its lateral movement above the cutter until the cutting operation is performed, and causing the strand to bow slightly during the cutting operation, the strand can be cut. It has been found that a very good "square" shape can be obtained without any mechanical complexity in the traverse of the cutter, as long as the strand is left fairly flexible, and the cutter tends to support the strand during the cutting operation and is not pushed out during this cutting operation. The additional length is picked up by the bowing effect.

It is preferable to use a rotating disk blade for cutting, and the cutting is preferably carried out by a slicing action. It is desirable to keep the blade clean and the blade preferably uses a rotating disc that cleans the cutting edge after each complete revolution by passing it through a cleaning station which cleans the top and bottom surfaces of the blade. It has the elements to Such elements as required are abrasive pads,
It may also be a squeezing member or a scraper blade or a washing and wiping combination.

Use a suitably thin blade to minimize compressive force on the pellet surface during cutting.

The thickness of the part of the blade that penetrates the pellet is 0.1 to 0.
5LIIgn, preferably 0.2 to 0.4 mm.

Preferably, the strand is at least partially pressed against the cutting blade and held in the cutting position by blowing gas onto the strand. If the strand is pressed against the blade only by the support surface, the strand may stick to the blade and this further reduces deformation of the strand.

K-RI Once one embodiment of the invention will be described with reference to the accompanying drawings, the apparatus of the invention is shown in plan view in FIG. 1 and in side elevation view in FIG.

A feed mechanism (not shown) is equipped with a circumferential grooved wheel that conveys the extruded strand to be cut at a steady speed. The guide 2 receives the strand and holds it during the cutting operation, and air ducts 4, 5 are provided for blowing air onto the strand alternately from both sides depending on the cutting action.

A carrier 3 supports a cutting disc 6, the circumference of which is up to the cutting edge is 0.3mm thick.

The disk is driven by flexible drive means 7 via a transmission (not shown) of carrier 3. This type of drive means makes it possible to reduce the mass of the carrier 3 and thus reduces the momentum compared to having an electric motor mounted on the carrier 3 for driving the cutting disc.6 The carrier 3 is a pneumatically controlled rod. 8 is caused to move between points on each side of the guide 2 in response to signals from an adjusting device (not shown) which adjusts the length of the strand feed and when the strand has been fed a predetermined length. The carrier 3 is moved between its two extremes. Therefore, cut the strands into uniform lengths.

The carrier 3 is supported on guides 9, 10, which are protected from dust by impermeable compressible elastic sleeves, two of these sleeves 12, 13.
is shown with one end fixed to the carrier 3 and the other end fixed to the ends of the guides 9,10. Holter 11 holds cleaning pads (not shown) above and below the disk. A chute 14 is provided for receiving the separated pellets.

January - January The device of the invention works as follows.

The disk 6 is rotated to feed the strand. Upon feeding a predetermined length of strand, a regulating device regulating the movement of the strand feed wheel activates the pneumatically controlled rod 8 to move the carrier 3 to the opposite location, thus cutting the strand at the same time. Air is allowed to flow into the opposite air duct 4 or 5 to support the strand against the cutting action. The pellets separated from the strand fall into the chute 14.

Each complete revolution of the disc 6, a pad held in a holder removes debris from the part of the disc that contacts the strands.

It has been found that during the cutting action a sufficient lifting effect is applied to the strand to cause it to bow slightly, so that with a suitably rapid cutting action the strand can be cut exactly "square". The 7-hole cylindrical pellets of ICI patent case H33277 and the extruded alpha alumina composition of European patent application no. The excellent geometric shape was then maintained.

[Brief explanation of drawings]

FIG. 1 is a plan view of the apparatus of the invention, and FIG. 2 is a side elevational view of the apparatus of the invention. 6...Blade 7...Means for passing the blade (5 other people)

Claims (1)

Claims: 1) Extruding a strand of deformable pellet-forming material, feeding the strand downward under the action of gravity, and cutting the strand horizontally by passing a blade substantially horizontally across the strand to form the strand. A method of forming pellets, characterized in that the pellets are cut from a strand while the strand is in a deformable state. 2) The method of claim 1, wherein the strand is at least partially pressed against the cutting blade and held in the cutting position by blowing gas onto the strand. 3) The method according to claim 1, wherein the pellets are then hardened by heat treatment. 4) The method of any one of claims 1, 2 or 3, wherein the pellets are generally cylindrical and have from 3 to 50 internal longitudinal holes passing through each pellet. 5) The motion of the cutter with the blade is horizontal, extruding the strands continuously and cutting the strands of sufficient length without significantly restricting lateral movement so that the strands hang in a flexible state above the cutter. A method according to any one of the preceding clauses in which the strand is bowed during operation to take up additional length of strand extruded during the cutting operation. 6) Any one of the above methods of cutting the strand into thin slices. 7) The method according to any one of the above items, in which the blade is a thin rotating disk blade. 8) The method according to claim 7, in which the blade is continuously cleaned. 9) comprising an extruder adapted to extrude a strand of deformable material and to feed the strand downwardly under the action of gravity, and means for cutting the strand by passing a blade substantially horizontally across the strand; Features: A device for forming pellets. 10) The apparatus of claim 9, wherein the means for cutting the strand is actuated to cut the strand by means of a device for adjusting the length of the fed strand.